Check the proof size is a multiple of 60

rvsol/src/RISCV.sol

@@ -346,6 +346,13 @@ contract RISCV is IBigStepper {
             }
             if iszero(eq(_proof.offset, proofContentOffset())) { revert(0, 0) }
 
+            if mod(calldataload(sub(proofContentOffset(), 32)), 60) {
+                // proof offset must be stateContentOffset+paddedStateSize+32
+                // proof size: 64-5+1=60 * 32 byte leaf,
+                // so the proofSize must be a multiple of 60
+                revert(0, 0)
+            }
+
             //
             // State loading
             //

rvsol/test/RISCV.t.sol

@@ -2371,11 +2371,23 @@ contract RISCV_Test is CommonTest {
         riscv.step(encodedState, proof, 0);
     }
 
+    function test_invalid_proof_size() public {
+        uint32 insn = encodeRType(0xff, 0, 0, 0, 0, 0);
+        (State memory state, bytes memory proof) = constructRISCVState(0, insn);
+        bytes memory encodedState = encodeState(state);
+        proof = hex"00"; // Invalid memory proof size
+
+        vm.expectRevert();
+        riscv.step(encodedState, proof, 0);
+    }
+
     function test_invalid_proof() public {
         uint32 insn = encodeRType(0xff, 0, 0, 0, 0, 0);
         (State memory state, bytes memory proof) = constructRISCVState(0, insn);
         bytes memory encodedState = encodeState(state);
-        proof = hex"00"; // Invalid memory proof
+        // Invalid memory proof
+        proof =
+            hex"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000";
 
         vm.expectRevert(hex"00000000000000000000000000000000000000000000000000000000badf00d1");
         riscv.step(encodedState, proof, 0);